The Drainage Report is a significant component of a Drainage Control Plan. The report contains the analysis, engineering computations, and soils report information that formulate the basis of the designs that are reflected on the Site Development Drawings. The Drainage Report includes information on existing site conditions, infiltration rates, soil types, downstream analyses, facility sizing, drainage basin mapping, and floodplain analyses. The report must be prepared by a professional engineer. See section 3.3.4 in Volume I of the Pierce County Stormwater Management and Site Development Manual
for further information on Drainage Reports.